Coal will nearly overtake oil as the dominant energy source by 2017, and only a drop in world gas prices could curb the use of the dirtier fossil fuel in the absence of high carbon prices, the International Energy Agency said.

The IEA, the energy agency for developed countries, said earlier this year that without a major shift away from coal, average global temperatures could rise by 6 degrees Celsius by 2050, leading to devastating climate change.

China will use more coal than the rest of the world put together, while India will overtake the United States as the world’s second-largest consumer and become the biggest global importer, the Paris-based IEA forecast in its annual Medium-Term Coal Market Report, released on Tuesday.

“Coal’s share of the global energy mix continues to grow each year, and if no changes are made to current policies, coal will catch oil within a decade,” IEA Executive Director Maria van der Hoeven said in a statement.

Use of the highly-polluting fossil fuel has surged in the past decade, mainly because of stronger demand from China and India, where cheap coal-fired electricity has helped to drive breakneck economic growth.

Coal now accounts for 28% of total primary energy consumption, and demand for the fossil fuel rose 4.3% in 2011 compared with 2010, the report said, underlining the world’s continued addiction to a fuel source that helped turn the wheels of the 19th century industrial revolution.

The world will burn around 1.2 billion more tonnes of coal per year by 2017 than it does today, which equals the current coal consumption of Russia and the United States combined, the IEA chief said.

Global coal consumption is likely to reach 4.32 billion tonnes of oil equivalent (btoe) by 2017, compared with 4.4 btoe for oil, although the pace of growth is likely to be slower than over the past decade, the IEA forecast.

Growth in coal use in developing countries will grow 3.9% a year on average over the next five years if economies such as China return to previous patterns of economic growth, the report said, while coal use in developed nations would only fall 0.7% by 2017.

”Coal remains the backbone of the OECD power system throughout the outlook period,“ the report said.